Immunology Exam #2

Front 1

Where are the HLA/MHC genes found in humans?

Back 1

Chromosme #6

Front 2

Identify the three types of MHC molecules and where they are found.

Back 2

Class I: most nucleated cells
Class II: professional APCs (m + B + dc)
Class III: secreted proteins found in serum

Front 3

MHC I genes present to ____?

Gene locus is ____?

Back 3

CD8+ Tcells (ex. Tc)

HLA-A, B & C in humans

Front 4

MHC II genes present to ____?

Gene locus is ____?

Back 4

CD4+ Tcells (Th)

HLA-DP, HLA-DQ, HLA-DR in humans

Front 5

HLA definition

Back 5

A gene product of the major histocompatibility complex; these antigens have been shown to have a strong influence on human allotransplantation, transfusions in refractory patients, and certain disease associations.

Front 6

MHC III genes present to____?

Gene locus is ____?

Back 6

do not directly present Ag to Tcells

code for:
complement Pr-
cytokines (TNF)
Ag processing Pr- (TAP, LMP2 & LMP7)

Front 7

What is the difference between MHC I and MHC II?

Back 7

I = single chain pr- associated with 2nd pr- not encoded for by MHC locus (beta2)
II: heterodimers coded for by the alpha and beta genes encoded within MHC locus

Front 8

what is the beta 2 microglobulin?

Back 8

the protein located within MHC I (an invariant chain) located on chromosome 15. it is the "crutch" which holds the Ag peptide area out to the Tcell

Front 9

haplotype definition:

Back 9

The alleles found on a single chromosome present at the known polymorphic sites in a gene or region of genomic DNA. The two haplotypes of a gene carried by an individual are that individual's alleles for the gene.

Front 10

how many MHC I variants are there?

MHC II?

Back 10

6 different MHC I

12 different MHC II

Front 11

why are MHC proteins considered to be highly polymorphic?

Back 11

1. co-dominant, both alleles expressed at once.
2. closely linked, low recombination frequency.
3. both alleles provide haplotype

Front 12

why are MHC genes considered to be polygenic?

Back 12

1. multiple similar genes
2. 6 class I and 12 class II
a. multiple dr-beta genes found in one person, and each can associate with the same/different dr-alpha genes. this increases diversity.

Front 13

define classical MHC genes v. non-classical

Back 13

c: T cell recognition of Ag
(HLA-a, b & c. HLA-dp, dr, dq)

n: NK cells and others

Front 14

will the progeny of inbred mice be able to donate a graft to its parents?
receive a graft from its parents?

Back 14

the progeny expresses BOTH haplotypes of the parents, so it can accept grafts from the parents. If the mother were to receive a graft from F1, it would be rejected as it contains the father's MHC.

Front 15

with no recombination, what are the odds that siblings will be histocompatible?

with recombination?

Back 15

25%


2%

Front 16

what is the likelihood that two unrelated individuals have identical haplotypes?

Back 16

almost zero

Front 17

how does racial segregation affect this?

Back 17

tissue transplants often need to be from members of the same racial background, due to specific recombinations within that population.

Front 18

what is required within the MHC I molecule to bring it to the surface of the cell?

Back 18

association of the large alpha chain with the invariant beta-2 microglobulin (which has no actual interaction with the Ag)

Front 19

what are the three domains of the MHC I protein? what are their functions?

Back 19

alpha 1 & 2 form the peptide binding cleft (8-10 aa)

alpha 3 interacts with CD8. it is structurally similar to beta-2 (via Ig constant region)and is relatively invariable.

Front 20

what is the structure and function of the MHC II protein?

Back 20

it's a heterodimer of alpha and beta chains, each is encoded for by different genes.

alpha 1/beta 1 = Ag binding cleft

alpha 2/beta 2 = CD4 contact area

Front 21

MHC proteins are highly polymorphic because: (3)

Back 21

1. co-dominant, both alleles expressed at once.
2. closely linked, low recombination frequency.
3. both alleles provide haplotype

Front 22

MHC genes are polygenic because: (2)

Back 22

1. multiple similar genes
2. 6 class I and 12 class II
a. multiple dr-beta genes found in one person, and each can associate with the same/different dr-alpha genes. this increases diversity.

Front 23

define classical v. non-classical

Back 23

c: T cell recognition of Ag
(HLA-a, b & c. HLA-dp, dr, dq)

n: NK cells and others

Front 24

will the progeny of inbred mice be able to donate a graft to its parents?
receive a graft from its parents?

Back 24

the progeny expresses BOTH haplotypes of the parents, so it can accept grafts from the parents. If the mother were to receive a graft from F1, it would be rejected as it contains the father's MHC.

Front 25

with no recombination, what are the odds that siblings will be histocompatible?

with recombination?

Back 25

25%


2%

Front 26

what is the likelihood that two unrelated individuals have identical haplotypes?

Back 26

almost zero

Front 27

how does racial segregation affect this?

Back 27

tissue transplants often need to be from members of the same racial background, due to specific recombinations within that population.

Front 28

what is required within the MHC I molecule to bring it to the surface of the cell?

Back 28

association of the large alpha chain with the invariant beta-2 microglobulin (which has no actual interaction with the Ag)

Front 29

what are the three domains of the MHC I protein? what are their functions?

Back 29

alpha 1 & 2 form the peptide binding cleft (8-10 aa)

alpha 3 interacts with CD8. it is structurally similar to beta-2 (via Ig constant region)and is relatively invariable.

Front 30

what is the structure and function of the MHC II protein?

Back 30

it's a heterodimer of alpha and beta chains, each is encoded for by different genes.

alpha 1/beta 1 = Ag binding cleft

alpha 2/beta 2 = CD4 contact area

Front 31

is MHC Ag binding specific?

Back 31

NO. a given MHC can bind a variety of Ag peptides

Front 32

what is the difference between class I and II binding sites?

Back 32

class I is BLOCKED at ends, holds smaller peptides and anchors the residues at #2 and #9.

class II is OPEN at ends, holds larger peptides (13-18) and anchors aren't specific. negatively charged position at #4, hydrophobic at #9.

Front 33

what types of peptides do MHC class I molecules present?

where do the Ag and MHC associate?

Back 33

endogenous peptides (ie viral)

Antigenic peptide and MHC I interact in the ER

Front 34

how many MHC I molecules are present on the surface of a cell?

Back 34

10^5

Front 35

how many peptides are needed for recognition

what is their preferred chain length?

Back 35

100 for recognition.

nonamers are preferred (8-10)

Front 36

which amino acids are usually recognized by the TCR?
what is their structure?

which amino acids contact the MHC?

Back 36

4-7 are usually recognized by the TCR. they form a 'bulge'.

1/2 and 8/9 contact the MHC.

Front 37

where is the greatest degree of variability found within the MHC I?

Back 37

alpha 1 & alpha 2 domains b/c they hold the antigenic peptide.

Front 38

what types of peptides do MHC class II molecules present?

how are the peptides degraded?

Back 38

they present exogenous peptides.

they are degraded via the endocytic pathway.

Front 39

how large are the antigenic peptides bound by class II?

Back 39

at least 13 amino acids. 9 amino acids are within the cleft.

Front 40

what is the binding domain of class II? does the peptide bulge like in class I?

Back 40

the binding domain is alpha 1/beta 1. there is a lesser bulge present.